Choosing the Best Almond Rootstock for Your Orchard

Roger Duncan

Pomology Advisor

UC Cooperative Extension Stanislaus County

What is the best rootstock?

What Do We Want in an Almond Rootstock?

•Compatibility

•Strong vigor / high yield efficiency

•Good anchorage

•Low / no suckering

•Tolerance to “heart rot” / wood decay fungi

Nemaguard

Advantages “Immune” to rootknot nematode Vigorous rootstock Compatible with all almond varieties Performs well in sandy loam & loam soils “Decent” anchorage

Nemaguard

Disadvantages Susceptible to: Ring & root lesion nematodes Bacterial canker High soil pH / high lime Salt (sodium, chloride, boron) Phytophthora / “wet feet” Oak root fungus Crown gall “Heart” rot / wood decay fungi

Lovell

Very similar to nemaguard in many ways

About 90% the size of nemaguard in sandy loam soils A little better than nemaguard in heavy soil Highly susceptible to rootknot nematode More tolerant to ring nematode than most

other commercial stocks

Peach / Almond Hybrids

Includes Hansen, Nickels, Bright’s Hybrid Cornerstone, Titan Hybrid, Paramount

Advantages Very high vigor Tolerant to high lime / high pH soils Tolerant to high boron, sodium & chloride Very good anchorage Resistant to rootknot nematode

Peach / Almond Hybrids

Disadvantages Very high vigor Highly susceptible to ring nematode and

bacterial canker Highly susceptible to most root diseases Phytophthora oak root fungus crown gall

Nemaguard Nickels

5th leaf

Yield (kernel pounds per acre) of Nonpareil & Carmel Almond Trees in 2010 (8th Leaf) & Cumulatively (4th – 8th Leaf).

Nonpareil Carmel 2010

(8th leaf) Cumulative

(4th – 8th leaf) 2010

(8th leaf) Cumulative

(4th – 8th leaf) Paramount -- -- 3600 a 17,075 Nickels 3204 a 14,719 3529 a 18,744 Hansen 536 3139 a 15,113 3549 a 17,415 Cornerstone 2907 a 14,460 -- -- Empyrean #1 2668 ab 14,194 3405* 16,914* Atlas 2599 b 12,428 3111 ab 16,140 Avimag 2328 bc 12,059 3085 ab 14,786 Viking 2235 bc 11,447 2569 b 13,354 Guardian 2143 bc 11,273 2398 b 12,391 Lovell 2103 bc 10,897 2455 b 11,486 Nemaguard 1946 c 10,884 2614 b 11,884 Empyrean 101 1357 d 6,028 -- -- Empyrean 2 965* 5,182* 1268* -- Julior -- -- 924* --

Salinity Tolerance of P/A Hybrid Rootstocks Atwater rootstock trial, 2006

Na (%) Cl (%)

Nemaguard 0.64 0.22

Lovell 0.72 0.26

Hansen 0.17 0.09

Brights 0.20 0.07

Critical level >0.25% > 0.3%

Effect of Rootstock on Hullsplit of Nonpareil Almond. July 30, 2008

0 20 40 60 80 100

Penta

Nemaguard

Adesoto

Viking

Kuban

Atlas

Guardian

Lovell

Paramount

Cadaman

Hansen

Cornerstone

Barrier 1

Nickels

Percent hullsplit

A

BC

B

B

B

AB

AB

AB

E

DE

DE

CDE

BCD

BCD

Nickels dead from Phytophthora –

spring 2007

Crown Gall on Hansen Rootstock

•Highly correlated to ring nematode

•Sand / loamy sand

•Replanted orchards

Bacterial Canker

Complex Hybrids

Viking (peach x almond x plum x apricot) Similar in size to nemaguard Resistant to rootknot nematode Tolerant to ring nematode Bacterial canker tolerance is similar to Lovell

but with higher yields More tolerant to high pH, sodium & chloride

than peach rootstocks Good anchorage

Soil Numbers of Pathogenic Nematodes as Influenced by Almond Rootstock

Escalon, CA. January, 2005

A Comparison of Almond Rootstocks for Incidence of Bacterial Canker

Escalon, CA 2005 (8th leaf)

0

10

20

30

40

50

60

Perc

en

t T

rees A

ffecte

d

Hansen Nickels Bright's Atlas Nema Guardian Lovell Viking

A

AB

CD

B

BC

D D D

Peach / almond hybrid rootstocks are very susceptible to bacterial canker

Viking, Lovell & Guardian are tolerant

Complex Hybrids

Atlas – (peach x almond x plum x apricot) More tolerant to high pH, sodium & chloride than

peach rootstocks

Has shown high yield efficiency in several UC trials

Resistant to rootknot nematode

Susceptible to ring nematode and bacterial canker

Unknown susceptibility to other root diseases

Rootstock Influences on Tree Nutrition Escalon Rootstock Trial Leaf Analyses, July 2004

Nemaguard 0.09 a Lovell 0.08 a Guardian 0.08 a Atlas 0.04 b Viking 0.04 b Nickels 0.03 b Brights 0.03 b Hansen 0.03 b

Chloride (%)

Rootstock Influences on Tree Nutrition Escalon Rootstock Trial Leaf Analyses, July 2004

Nemaguard 47 a Lovell 47 a Guardian 47 a Atlas 49 a Viking 45 ab Nickels 42 bc Brights 42 bc Hansen 40 c

Boron (ppm)

Alternative Rootstocks Being Tested in Stanislaus County for Almond

Krymsk 86 – Russia Plum (Myrobalan) x peach

– 80 – 90% size of nemaguard (similar to Lovell)

• Reported to be… – Tolerant to heavy soils, root rot. – Good anchorage – Very little suckering – Appears to be very compatible with almond*

Yield of 5th Leaf Butte & Padre on Plum Rootstocks October 2011

•Empyrean 1 (Barrier 1) – Italy

Peach

•More vigorous than P / A hybrids

•Resistant to rootknot nematode

•So far, very few ring nematodes in local trial

Alternative Rootstocks Being Tested in Stanislaus County for Almond

Yield (kernel pounds per acre) of Nonpareil & Carmel Almond Trees in 2010 (8th Leaf) & Cumulatively (4th – 8th Leaf).

Nonpareil Carmel 2010

(8th leaf) Cumulative

(4th – 8th leaf) 2010

(8th leaf) Cumulative

(4th – 8th leaf) Paramount -- -- 3600 a 17,075 Nickels 3204 a 14,719 3529 a 18,744 Hansen 536 3139 a 15,113 3549 a 17,415 Cornerstone 2907 a 14,460 -- -- Empyrean #1 2668 ab 14,194 3405* 16,914* Atlas 2599 b 12,428 3111 ab 16,140 Avimag 2328 bc 12,059 3085 ab 14,786 Viking 2235 bc 11,447 2569 b 13,354 Guardian 2143 bc 11,273 2398 b 12,391 Lovell 2103 bc 10,897 2455 b 11,486 Nemaguard 1946 c 10,884 2614 b 11,884 Empyrean 101 1357 d 6,028 -- -- Empyrean 2 965* 5,182* 1268* -- Julior -- -- 924* --

Specific Challenges…

• Alkaline / salty soil or water – P/A hybrid (not if heavy soil or ring nematodes)

• Hansen, Nickels, Brights, Paramount, – Atlas (not if ring nematodes) – Viking – Empyrean 1 or Cadaman??

Specific Challenges…

• Poor drainage / heavy soil

– Marianna 26-24

– Krymsk 86

– Marianna 40

– Ishtara

– Hiawatha ? Penta? Tetra? Empyrean 101?

More vigorous than M 26-24 with little suckering }

Number of Suckers / Tree May, 2011

Rootstock Effect on Tree Size of Fourth-Leaf Butte Almond Trees.

December, 2010.

a a

ab ab

bc bcd

cd cd d

Specific Challenges…

• Oak root fungus

– Marianna 26-24 is the only known commercially available almond rootstock with ORF tolerance

Don’t ignore the bottom half of the tree!

Think about what specific challenges your ground may have and select the

appropriate rootstock.

Your best offense is a good defense.

Thank you for your attention